'Bonding' Gene Found in Men

Sept. 2, 2008 -- Researchers have identified a "bonding" gene involved in the relationship behavior of men and their partners.

Researchers, led by Hasse Walum of the Karolinkska Institute in Stockholm, Sweden, looked at pairs of Swedish twins.

Five hundred fifty-two twins and their partners of at least five years were studied. Most (82%) were married. Eighteen percent were living together but not married.

They were given a questionnaire, visited at home by researchers, and had DNA tests.

The researchers also looked at how the participants scored on a test that estimates how bonded one is to one's mate.

Men with a certain variation of the AVPR1A gene got low scores on the bonding test and were not as likely to be married as men who did not have that gene variation.

If a man had two copies of the genetic variation, their chances of reporting that they had a martial crisis in the past year doubled.

Women who reported that they were the most satisfied with their marriages were in relationships with men who did not have the gene variation.

Researchers write that the findings show a "modest but significant influence of the gene," which they add shows that previous research done on voles (a type of rodent) may prove true for humans.

The "bonding gene" theory was first tested on the humble prairie vole and its relatives. Prairie voles are often studied for their human-like social qualities, such as picking one mate for life.

The researchers cite a vole study which found that the more bonded and social prairie vole had a genetic makeup that differed from their less social and more sexually adventurous cousins, the montane and meadow vole.

When the gene was transferred into non-monogamous mice, the mice's social behavior became more like prairie voles.

The study results are published in the Sept. 2 edition of Proceedings of the National Academy of Sciences.